The present invention relates to an automotive alternator including a rectifier.
In recent years, as the demand for electric instruments grows in an automobile, there is a trend toward higher power output in automotive alternators. With such increase in power output in an automotive alternator, a problem arises in that as the output current increases, the heat generation of each part increases, leading to a reduction of the lifetime thereof due to temperature increase.
Particularly, a rectifier element, which rectifies an alternate current generated by the automotive alternator, is significantly affected by temperatures caused by heat generation and exhibits a sharp decline of lifetime when a heat resistant temperature is exceeded.
Further, in addition to the increase of heat generation due to an increase in output current, there is an increasing trend in temperature of the ambient environment where an automotive alternator is mounted, as the result of the space reduction in the engine room in recent years, and thus a temperature reduction by increasing the cooling performance of a rectifier element has become an important issue.
Accordingly, for the improvement of cooling efficiency of a rectifier, JPA-2009-60711 proposes to reduce the temperature of rectifier element by exploiting an axial flow in a limited space and devising the shape of heat dissipating fin to increase the cooling efficiency of heat dissipating plate.
Moreover, for the improvement of cooling efficiency of a rectifier, JP-A-11-164538 proposes to reduce a temperature of a rectifier element by allowing cooling air from the outside to efficiently flow into and pass through between a rectifier element of positive pole and a protection cover and, in the case of a rectifier element of negative pole, between a rear frame and a second heat dissipating plate, thereby improving the cooling effect of heat dissipating plates. Thus, cooling of the rectifier element of an automotive alternator is achieved by the optimization of the shape and the expansion of the heat dissipating area of heat dissipating fins, the optimization of the flow path of cooling air, and so on.